Rpi4 + Grove Base Hat + Temperature Sensor V1.2 bad temperature reading

Hi all,

I have this combination Rpi4 + Grove Base Hat and 2x Temperature Sensor V1.2. Software is latest raspberryPi OS and grove.py-0.6 (Seeed-Studio) installed from git. I have two temp sensors and trying monitor inside vs outside temperature. its looks like inside both show correct temperature (24) but in outside where is about 0-2 °C both start slowly droping from 24 to 12 and there stay for days. After putting them inside they are instantly back in 24. Very strange behavior.

using default script
~/grove.py/grove $ python3 grove_temperature_sensor.py

tried both python2 and python3. Tried other ports -still same issue

any ideas?

Thank you